The aim of this study is to assess the potential for disruption of the lipid bilayer by C-60 suspended in water. We selected a C-60 suspension that has previously been shown to provoke cell membrane destabilisation in vivo. Phase contrast microscopy and computer aided image analysis results show that C-60 causes shape transformations and rupture of unilamellar phospholipid vesicles, indicative of changes in their average mean curvature. Small-angle X-ray scattering reveals that C-60 provokes disruptions of external membranes of multilamellar vesicles only after freeze and thaw cycles. Here, the liposomes undergo breakage and annealing steps which increase the probability for fullerenes to insert into the MLVs. Our experimental findings confirm the potential of C-60 to reconstruct lipids in biological membranes.
COBISS.SI-ID: 2451279
We have studied the genotoxicity of TiO2 particles with a Comet assay on a unicellular organism, Tetrahymena thermophila. Exposure to bulk or nano-TiO2 of free cells, cells embedded in gel or nuclei embedded in gel, all resulted in a positive Comet assay result but this outcome could not be confirmed by cytotoxicity measures such as lipid peroxidation, elevated reactive oxygen species or cell membrane composition. Published reports state that in the absence of cytotoxicity, nano- and bulk TiO2 genotoxicity do not occur directly and a possible explanation of our Comet assay results is that they are false positives resulting from post-festum exposure interactions between particles and DNA. We suggest that before Comet assay is used for nanoparticle genotoxicity testing, evidence for the possibility of post-festum exposure interactions should be considered. The acellular Comet test described in this report can be used for this purpose.
COBISS.SI-ID: 2573903
In order to study the effects of nanoparticles (NPs) with different physicochemical properties on cellular viability and structure, Saccharomyces cerevisiae were exposed to different concentrations of TiO2-NPs (1–3 nm), ZnO-NPs ((100 nm), CuO-NPs ((50 nm), their bulk forms, Ag-NPs (10 nm) and single-walled carbon nanotubes (SWCNTs). CuO-NPs were highly cytotoxic, reducing the cell density by 80% at 9 cm2/ml, and inducing lipid droplet formation. Cells exposed to Ag-NPs (19 cm2/ml) and TiO2-NPs (147 cm2/ml) contained dark deposits in intracellular vacuoles, the cell wall and vesicles, and reduced cell density (40 and 30%, respectively). ZnO-NPs (8 cm2/ml) caused an increase in the size of intracellular vacuoles, despite not being cytotoxic. SWCNTs did not cause cytotoxicity or significant alterations in ultrastructure, despite high oxidative potential. Two genotoxicity assays, GreenScreen and the comet assay, produced different results and the authors discuss the reasons for this discrepancy. Classical assays of toxicity may not be the most suitable for studying the effects of NPs in cellular systems, and the simultaneous assessment of other measures of the state of cells, such as TEM are highly recommended.
COBISS.SI-ID: 3220104
The aim of this study was to provide experimental evidence on the formation of Co2+, Fe2+ and Fe3+ ions from CoFe2O4 nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were assessed. Cell membrane stability was tested with a modified method for measurement of cell membrane stability. Proton induced x-ray emission and low energy synchrotron radiation X-ray fluorescence were used to study internalisation and distribution of Co and Fe. Co2+ ions were found to be more toxic than nanoparticles. The authores confirmed that Co2+ ions accumulate in the hepatopancreas but Fe+ ions or CoFe2O4 nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media.
COBISS.SI-ID: 2768975
In the current work, we used a test system with terrestrial isopods (Porcellio scaber) fed with food spiked with Cu NPs or soluble Cu salt for 14 days. Cu content was analyzed in the digestive glands, gut, and the 'rest' of the body. Similar patterns of (i) assimilated and depurated amounts of Cu, (ii) Cu body distribution, and (iii) effect on isopods feeding behavior were observed regardless of whether the animals were fed with Cu NPs or soluble Cu salt spiked food. Thus, Cu ions and not Cu NPs were assimilated by the digestive gland cells. The comparison of the in vitro data on solubilization of Cu NPs and in vivo data on Cu accumulation in the animal tissues showed that about 99% of accumulated copper ions was dissolved from ingested Cu NPs in the digestive system of isopods.
COBISS.SI-ID: 2658127